import java.util.Arrays;

public class MyPriorityQueue {
    public int[] elem;
    public int usedSize;

    public MyPriorityQueue() {
        elem = new int[10];
    }
    public void createElem(int[] array){
        for (int i = 0; i < array.length; i++) {
            if (isFull()){
                elem = Arrays.copyOf(elem,elem.length*2);
            }
            elem[i] = array[i];
            usedSize++;
        }
    }

    public void createHeap() {
        for (int i = (this.usedSize-1-1)/2; i >= 0; i--) {
            shiftDown(i,this.usedSize);
        }
    }

    /**
     *
     * @param parent 是每棵子树的根节点的下标
     * @param len  是每棵子树调整结束的结束条件
     * 向下调整的时间复杂度：O(logn)
     */
    private void shiftDown(int parent,int len) {
        int child = parent*2 + 1;
        while (child < len){
            if (child+1 < len && elem[child] < elem[child+1]){
                child++;
                }
            if (elem[child] > elem[parent]){
                swap(child,parent);
                parent = child;
                child = parent*2 + 1;
            }else {
                break;
            }
        }
    }
    private void swap(int a,int b){
        int tmp = elem[a];
        elem[a] = elem[b];
        elem[b] = tmp;
    }


    /**
     * 入队：仍然要保持是大根堆
     * @param val
     */
    public void push(int val) {
        if (isFull()){
            elem = Arrays.copyOf(elem,elem.length*2);
        }
        elem[usedSize] = val;
        shiftUp(usedSize);
        usedSize++;
    }

    private void shiftUp(int child) {
        int parent = (child-1)/2;
        while(parent >= 0){
            if (elem[child] > elem[parent]){
                swap(child,parent);
                child = parent;
                parent = (parent-1)/2;
            }else{
                break;
            }
        }
    }

    public boolean isFull() {
        return usedSize == elem.length;
    }

    /**
     * 出队【删除】：每次删除的都是优先级高的元素
     * 仍然要保持是大根堆
     */
    public int pollHeap() {
        if (isEmpty()){
            return -1;
        }
        int val = elem[0];
        swap(0,usedSize-1);
        shiftDown(0,usedSize-1);
        usedSize--;
        return val;
    }

    public boolean isEmpty() {
        return usedSize == 0;
    }

    /**
     * 获取堆顶元素
     * @return
     */
    public int peekHeap() {
        if (isEmpty()){
            return -1;
        }
        return elem[0];
    }

    public void heapSort() {
        int end = usedSize - 1;
        while (end > 0) {
            swap(0, end);
            shiftDown(0, end);
            end--;
        }
    }
}
